A SURVEY OF THE WESTERN BLUE GROPER ON SOUTHERN YORKE PENINSULA By Scoresby A. Shepherd and James B. Brook Reefwatch, c/o Conservation Council of South Australia, 120 Wakefield St, Adelaide, 5000. 24 January 2003 Photo: Adrian Brown 1 A SURVEY OF THE WESTERN BLUE GROPER ON SOUTHERN YORKE PENINSULA, SOUTH AUSTRALIA by Scoresby A. Shepherd 1 and James B. Brook2 1Senior Research Fellow, South Australian Research and Development Institute, PO Box 120 Henley Beach. 5022. Email address:
[email protected] 2PO Box 111 Normanville, SA. 5204. Email address:
[email protected] SUMMARY Thirteen sites on southern Yorke Peninsula were surveyed in order to estimate the abundance of the western blue groper, Achoerodus gouldii. Juveniles (<20 cm) were sporadically common at shallow, moderately sheltered sites in creviced rocky areas. Sub-adults (20-60 cm) occurred at depths of 2-6 m and their abundance was correlated with that of juveniles, suggesting local recruitment of juveniles to adjacent reefs. Sub-adults > 30 cm were rare and adults (> 60 cm) even rarer. Anecdotal evidence from the 1960s to the 1980s was that adult groper were once common off headlands of SW Yorke Pen. Using the mean size of adult blue-throated wrasse as an index of fishing intensity, we found a correlation between this index and the mean size of sub-adults. The correlation implies that, despite formal protection of the blue groper, fishing mortality may be a contributing factor to the rarity of sub-adults in in-shore waters. Measures such as no-take reserves would give better protection to this species on open coasts.